Although this oversight could theoretically result in a
corrupted index, it is unlikely to have caused any problems
in practice, since the active part of a GIN metapage is
smaller than a standard 512-byte disk sector.

This code never worked correctly, and since the case is
neither specified by the SQL standard nor documented, it
seemed better to remove it than fix it.

Avoid getting more than AccessShareLock when de-parsing a rule or
view (Dean Rasheed)

This oversight resulted in pg_dump unexpectedly acquiring
RowExclusiveLock locks on tables
mentioned as the targets of INSERT/UPDATE/DELETE
commands in rules. While usually harmless, that could
interfere with concurrent transactions that tried to
acquire, for example, ShareLock on
those tables.

This change fixes a significant performance problem that
occurred when there were many not-yet-committed rows at the
end of the index, which is a common situation for indexes
on sequentially-assigned values such as timestamps or
sequence-generated identifiers.

Fix test to see if hot standby connections can be
allowed immediately after a crash (Heikki Linnakangas)

Prevent interrupts while reporting non-ERROR messages (Tom Lane)

This guards against rare server-process freezeups due to
recursive entry to syslog(),
and perhaps other related problems.